 <style type="text/css" media="screen">

        /*#loginBox {
          background-color: #D9FFA7;
          border: 1px solid green;
        }*/

        #box
        {
          width: 220px;
        }
        #usernick
        {
          color: white;
        }
        #logoutlink
        {
          text-align: right;
        }

 </style>

<div id="box">

  Bienvenido &nbsp;<span id="usernick"><sec:username/></span> 
  <p id="logoutlink">(<g:link controller='logout'>Logout</g:link>)</p>

 </div>